Actually this is pretty easy to achieve. Say a POD around 247 BC the greeks who translated the Septuagint get something messed up or otherwise go a bit mad. They accidentally switch Satan's name for St. Michael the Archangel. Spelling it Sataniel. This goes uncorrected for many centuries.
Flash forward to St. Paul and the spreading of the New Testament, the kind actions of St. Satan are spread all around the Roman Empire along with the rest of Christian theology. Nothing so far is changed, as far as butterflies is considered.
Constantine converts to Christianity, he proclaims to have been guided to the light by Sataniel.
Fall of Rome goes by. Dark Ages ensue. Some butterflies occur changing some names and gently alter the time line in subtle ways. Centuries later the so-called Middle Ages come around, and bang in 1254 Pope Gregory VIII, gives his support to the creation of the Order of Satan. An organization dedicated to Crusade against the Tartars of Crimea.